1. Field of the Invention
This invention relates to hydrogen peroxide compositions useful for disinfection and sterilization of metal, ceramic and plastic surfaces, especially medical and dental equipment, for example, inhalation therapy equipment, and instruments which cannot be sterilized by steam.
2. Description of the Prior Art
Disinfection refers to destruction of vegetative microorganisms and viruses; sterilization additionally refers to destruction of microbial spores, thus, all microscopic life forms.
The currently used chemical disinfectants and sterilants are ethylene oxide and compositions of aldehydes, especially formaldehyde, and dialdehydes, especially glutaraldehyde.
Ethylene oxide is a gas at ordinary temperatures and pressures and is used in gaseous form. It is an irritant to human tissues. After sterilization long periods of aeration (8 to 24 hours) are required for desorption of residual ethylene oxide from instruments sufficient to avoid irritation by the instruments during reuse.
Glutaraldehyde is used alone or in combination with formaldehyde in the form of aqueous compositions. The aldehydic fumes of the compositions are irritating to the eyes and nose, and in some cases to the skin, of the user. A currently sold and used alkaline glutaraldehyde composition is recommended for cold (20.degree. C.) sterilization but is not recommended for warm (50.degree. C.) sterilization.
Hydrogen peroxide is known to be a potent, non-irritating germicide and has been used for many years as a topical antiseptic (The Merck Index, Ninth Edition, Monograph 4691), especially as a 3 percent aqueous solution (ibid., Monograph 4692), but has not been widely used for disinfection and sterilization due to its instability and its corrosiveness to metal surfaces. The decomposition of hydrogen peroxide to water and oxygen is catalyzed by the enzyme, catalase, which is present in organic matter. Residual organic matter from used medical and dental equipment and instruments, which is contacted with hydrogen peroxide during use of disinfecting and sterilizing compositions thereof, therefore accelerates the decomposition and shortens the time during which the compositions can be reused. Although the stability of hydrogen peroxide is known to be increased by the presence of acids (ibid., Monograph 4691), which are believed to denature and therefore prevent the catalytic effect of the catalase, hydrogen peroxide disinfecting and sterilizing compositions which are sufficiently stable to the presence of organic matter to be practical, i.e., reusable over an extended period of time, are not known.
The present invention therefore satisfies the need for a non-irritating and less corrosive hydrogen peroxide disinfecting and sterilizing composition which is stable against organic matter contamination and maintains full antimicrobial effectiveness on repeated use at ambient and elevated temperatures over an extended period of time.